Suppose you have computed 2 or 3 linear regression equations, and you wish to view the plots of the regression lines. This is often useful to make a quick determination of whether the lines intersect within the range of Y values of interest. This can be done, with some work, within some of the more expensive or technically challenging statistical systems (e.g., SPSS, Stata, R), but for people without the funds or skills to access these capabilities through these high level systems, there has been no readily accessible, easy to use tool for producing such graphs. This macro responds to this need. Just fill in the information requested and your graph is generated. It also computes the line intersections and reports whether the intersections occur within the range of Y encompassed by the graph.
Note that this tool will also work with multiple linear regression models as well as with simple linear regression models. To use with multiple regression models, you will have to compute the predicted values for your models, and then compute the simple regression of the observed Y values on the predicted Y values for each model. Use the slopes, intercepts, and minimums and maximums for these models to generate the graphs (the predicted Y variable will be the X variable in these analyses).
The Correlation and Slope Comparator can be downloaded by clicking this link:
Regression Graph Creator (Excel worksheet calculators)